Unification of rice parameter lookup table

Abstract

According to an embodiment, a method of selecting a Rice parameter for encoding a video bitstream using at least one processor includes obtaining an absolute level corresponding to a current transform block; determining whether transform skip is enabled; generating a lookup variable based on the absolute level and the determination of whether the transform skip is enabled; obtaining the Rice parameter from a lookup table based on the lookup variable; and encoding a residual subblock based on the Rice parameter.

What is claimed is: 
     
       1. A method of selecting a Rice parameter for encoding a video bitstream using at least one processor, the method comprising:
 obtaining an absolute level corresponding to a current transform block; 
 determining whether transform skip is enabled; 
 generating a lookup variable based on the absolute level and the determination of whether the transform skip is enabled; 
 obtaining the Rice parameter from a single lookup table based on the lookup variable when the transform skip is enabled and when the transform skip is disabled; 
 based on determining that the transform skip is disabled, generating an adjusted variable by adjusting the absolute level based on a base level corresponding to the current transform block; 
 generating the lookup variable by clipping the adjusted variable such that, based on the lookup variable being outside a first clipping value and a second clipping value, adjusting the lookup variable to be between the first clipping value and the second clipping value; and 
 encoding a residual subblock based on the Rice parameter. 
 
     
     
       2. The method of  claim 1 , further comprising:
 based on determining that the transform skip is enabled, generating the adjusted variable by further adjusting the absolute level. 
 
     
     
       3. The method of  claim 1 , further comprising:
 based on determining that the transform skip is enabled, generating an offset variable by applying an offset to the absolute level; and 
 generating the lookup variable by clipping the offset variable. 
 
     
     
       4. The method of  claim 1 , further comprising:
 based on determining that the transform skip is enabled, generating the adjusted variable by clipping the absolute level; and 
 generating the lookup variable by applying an offset to the adjusted variable. 
 
     
     
       5. The method of  claim 1 , wherein the determination of whether the transform skip is enabled is performed based on a transform skip flag. 
     
     
       6. The method of  claim 1 , wherein the lookup variable is determined based on at least one from among a color component index, a luma location specifying a top-left sample of the current transform block relative to a top-left sample of a current picture, a current coefficient scan location, a binary logarithm of a width of the current transform block, and a binary logarithm of a height of the current transform block. 
     
     
       7. The method of  claim 1 , wherein the Rice parameter has a value between 0 and 2. 
     
     
       8. The method of  claim 1 , wherein the Rice parameter has a value between 0 and 3. 
     
     
       9. A device for selecting a Rice parameter for encoding a video bitstream, the device comprising:
 at least one memory configured to store program code; and 
 at least one processor configured to read the program code and operate as instructed by the program code, the program code including: 
 first obtaining code configured to cause the at least one processor to obtain an absolute level corresponding to a current transform block; 
 determining code configured to cause the at least one processor to determine whether transform skip is enabled; 
 generating code configured to cause the at least one processor to generate a lookup variable based on the absolute level and the determination of whether the transform skip is enabled; 
 second obtaining code configured to cause the at least one processor to obtain the Rice parameter from a single lookup table based on the lookup variable when the transform skip is enabled and when the transform skip is disabled; 
 second generating code configured to, based on determining that the transform skip is disabled, generate an adjusted variable by adjusting the absolute level based on a base level corresponding to the current transform block; 
 third generating code configured to generate the lookup variable by clipping the adjusted variable such that, based on the lookup variable being outside a first clipping value and a second clipping value, adjust the lookup variable to be between the first clipping value and the second clipping value; and 
 encoding code configured to cause the at least one processor to encode a residual subblock based on the Rice parameter. 
 
     
     
       10. The device of  claim 9 , wherein the generating code comprises first generating code, and
 wherein the program code further comprises:
 fourth generating code configured to cause the at least one processor to, based on determining that the transform skip is enabled, generate the adjusted variable by further adjusting the absolute level. 
 
 
     
     
       11. The device of  claim 9 , wherein the generating code comprises first generating code, and
 wherein the program code further comprises:
 fourth generating code configured to cause the at least one processor to, based on determining that the transform skip is enabled, generate an offset variable by applying an offset to the absolute level; and 
 fifth generating code configured to cause the at least one processor to generate the lookup variable by clipping the offset variable. 
 
 
     
     
       12. The device of  claim 9 , further wherein the generating code comprises first generating code, and
 wherein the program code further comprises:
 fourth generating code configured to cause the at least one processor to, based on determining that the transform skip is enabled, generate the adjusted variable by clipping the absolute level; and 
 fifth generating code configured to cause the at least one processor to generate the lookup variable by applying an offset to the adjusted variable. 
 
 
     
     
       13. The device of  claim 9 , wherein the determination of whether the transform skip is enabled is performed based on a transform skip flag. 
     
     
       14. The device of  claim 9 , wherein the lookup variable is determined based on at least one from among a color component index, a luma location specifying a top-left sample of the current transform block relative to a top-left sample of a current picture, a current coefficient scan location, a binary logarithm of a width of the current transform block, and a binary logarithm of a height of the current transform block. 
     
     
       15. The device of  claim 9 , wherein the Rice parameter has a value between 0 and 3. 
     
     
       16. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions that, when executed by one or more processors of a device for selecting a Rice parameter for encoding a video bitstream, cause the one or more processors to:
 obtain an absolute level corresponding to a current transform block; 
 determine whether transform skip is enabled; 
 generate a lookup variable based on the absolute level and the determination of whether the transform skip is enabled; 
 obtain the Rice parameter from a single lookup table based on the lookup variable when the transform skip is enabled and when the transform skip is disabled; 
 based on determining that the transform skip is disabled, generate an adjusted variable by adjusting the absolute level based on a base level corresponding to the current transform block; 
 generate the lookup variable by clipping the adjusted variable such that, based on the lookup variable being outside a first clipping value and a second clipping value, adjust the lookup variable to be between the first clipping value and the second clipping value; and 
 encode a residual subblock based on the Rice parameter. 
 
     
     
       17. The non-transitory computer-readable medium of  claim 16 , wherein the determination of whether the transform skip is enabled is performed based on a transform skip flag. 
     
     
       18. The non-transitory computer-readable medium of  claim 16 , wherein the lookup variable is determined based on at least one from among a color component index, a luma location specifying a top-left sample of the current transform block relative to a top-left sample of a current picture, a current coefficient scan location, a binary logarithm of a width of the current transform block, and a binary logarithm of a height of the current transform block.